1. Field of Use
The present invention relates to data processing systems and, more specifically, to apparatus for testing such systems.
2. Prior Art
It is well known to provide special apparatus for verifying the operation of a data processing system. That is, certain systems include maintenance or auxiliary processing units for testing different systems during normal operation or during a test mode of operation. It is also well known to include an internal testing capability in the processing units of a system for establishing a certain level of operability.
The above arrangements tend to be quite complex or costly. Moreover, they do not provide the level of fault detection which is required for debugging a system or which can be used in a factory or repair facility environment. In such environments, tools, such as an in circuit emulator, are used to debug such systems or for determining failed board components.
The approach has been found to be costly and require that the personnel conducting such operations have some specific knowledge about the programming language(s) of the programs being executed during such testing. Additionally, since the connection of such emulators or similar test equipment are "intrusive," they can add timing delays which can make it more difficult to reliably ascertain the cause of the problem. This can become an acute problem where processing proceeds high speed, such as where the processing unit includes a high performance microprocessor chip as the main processing element.
Accordingly, it is a primary object of the present invention to provide testing apparatus and method which can reliably test a processing unit in a system and which also is usable in a factory test environment.